Parsing JSON from URL

Question

Is there any simplest way to parse JSON from a URL  I used Gson I can t find any helpful examples

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You could use org apache commons io IOUtils for downloading and org json JSONTokener for parsing   JSONObject jo    JSONObject  new JSONTokener IOUtils toString new URL  http   gdata youtube com feeds api videos SIFL9qfmu5U alt json     nextValue    System out println jo getString  version

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I use java 1 8 with com fasterxml jackson databind ObjectMapper  ObjectMapper mapper   new ObjectMapper    Integer      value   mapper readValue new URL  your url here    Integer class     Integer class can be also a complex type  Just for example used

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public static TargetClassJson downloadPaletteJson String url  throws IOException           if  StringUtils isBlank url                 return null                    String genreJson   IOUtils toString new URL url  openStream             return new Gson   fromJson genreJson  TargetClassJson class

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GSON has a builder that takes a Reader object  fromJson Reader json  Class classOfT     This means you can create a Reader from a URL and then pass it to Gson to consume the stream and do the deserialisation    Only three lines of relevant code   import java io InputStreamReader  import java net URL  import java util Map   import com google gson Gson   public class GsonFetchNetworkJson        public static void main String   ignored  throws Exception            URL url   new URL  https   httpbin org get color red amp shape oval            InputStreamReader reader   new InputStreamReader url openStream             MyDto dto   new Gson   fromJson reader  MyDto class               using the deserialized object         System out println dto headers           System out println dto args           System out println dto origin           System out println dto url              private class MyDto           Map lt String  String gt  headers          Map lt String  String gt  args          String origin          String url               If you happen to get a 403 error code with an endpoint which otherwise works fine  e g  with curl or other clients  then a possible cause could be that the endpoint expects a User-Agent header and by default Java URLConnection is not setting it  An easy fix is to add at the top of the file e g  System setProperty  http agent    Netscape 1 0

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Here is a easy method   First parse the JSON from url -  public String readJSONFeed String URL        StringBuilder stringBuilder   new StringBuilder        HttpClient httpClient   new DefaultHttpClient        HttpGet httpGet   new HttpGet URL        try            HttpResponse response   httpClient execute httpGet           StatusLine statusLine   response getStatusLine            int statusCode   statusLine getStatusCode             if  statusCode    200                 HttpEntity entity   response getEntity                InputStream inputStream   entity getContent                BufferedReader reader   new BufferedReader                      new InputStreamReader inputStream                String line              while   line   reader readLine       null                    stringBuilder append line                              inputStream close               else               Log d  JSON    Failed to download file                    catch  Exception e            Log d  readJSONFeed   e getLocalizedMessage               return stringBuilder toString        Then place a task and then read the desired value from JSON -  private class ReadPlacesFeedTask extends AsyncTask lt String  Void  String gt        protected String doInBackground String    urls             return readJSONFeed urls 0               protected void onPostExecute String result             JSONObject json          try               json   new JSONObject result                CREATE A JSON OBJECT              JSONObject data   json getJSONObject  JSON OBJECT NAME                 GET A STRING              String title   data getString                 Similarly you can get other types of data           Replace String to the desired data type like int or boolean etc             catch  JSONException e1                e1 printStackTrace                          GETTINGS DATA FROM JSON ARRAY            try                JSONObject jsonObject   new JSONObject result               JSONArray postalCodesItems   new JSONArray                      jsonObject getString  postalCodes                      JSONObject postalCodesItem   postalCodesItems                          getJSONObject 1              catch  Exception e                Log d  ReadPlacesFeedTask   e getLocalizedMessage                         You can then place a task like this -  new ReadPlacesFeedTask        execute  JSON URL

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A simple alternative solution    Paste the URL into a json to csv converter Open the CSV file in either Excel or Open Office Use the spreadsheet tools to parse the data

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import org apache commons httpclient util URIUtil   import org apache commons io FileUtils   import groovy json JsonSlurper   import java io File       tmpDir     defineYourTmpDir      URL url   new URL  http   yourOwnURL com file json        String path   tmpDir     tmpRemoteJson      json       remoteJsonFile   new File path       remoteJsonFile deleteOnExit         FileUtils copyURLToFile url  remoteJsonFile       String fileTMPPath   remoteJsonFile getPath         def inputTMPFile   new File fileTMPPath       remoteParsedJson   new JsonSlurper   parseText inputTMPFile text

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First you need to download the URL  as text    private static String readUrl String urlString  throws Exception       BufferedReader reader   null      try           URL url   new URL urlString           reader   new BufferedReader new InputStreamReader url openStream              StringBuffer buffer   new StringBuffer            int read          char   chars   new char 1024           while   read   reader read chars      -1              buffer append chars  0  read             return buffer toString          finally           if  reader    null              reader close             Then you need to parse it  and here you have some options     GSON  full example    static class Item       String title      String link      String description     static class Page       String title      String link      String description      String language      List lt Item gt  items     public static void main String   args  throws Exception        String json   readUrl  http   www javascriptkit com                                dhtmltutors javascriptkit json         Gson gson   new Gson                Page page   gson fromJson json  Page class        System out println page title       for  Item item   page items          System out println          item title       Outputs   javascriptkit com     Document Text Resizer     JavaScript Reference- Keyboard  Mouse Buttons Events     Dynamically loading an external JavaScript or CSS file  Try the java API from json org   try       JSONObject json   new JSONObject readUrl               String title    String  json get  title               catch  JSONException e        e printStackTrace

[java] Parsing JSON from URL

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